Bacterial fruit blotch

Bacterial fruit blotch, caused by the bacterium Acidovorax citrulli, is a severe plant disease that poses a major threat to cucurbit production worldwide. This pathogen is known for its ability to cause rapid crop failure, particularly in watermelon plantations, making it a critical concern for agricultural security.

The disease primarily affects watermelons, cantaloupes, and other members of the Cucurbitaceae family. Acidovorax citrulli is seed-borne, which allows the pathogen to travel long distances through trade. Once introduced into a field, it can survive in debris or weeds, acting as a recurring source of infection for subsequent growing seasons.

Symptoms typically begin with small, water-soaked lesions on the undersides of leaves and cotyledons. As the disease progresses, these lesions expand and turn necrotic. On fruits, the symptoms appear as water-soaked spots that darken and eventually cause cracks in the rind, leading to internal decay and a foul-smelling bacterial rot.

The development of the disease is highly dependent on environmental conditions, specifically high humidity and temperatures ranging from 25°C to 32°C. Frequent rainfall or overhead irrigation provides the necessary moisture for the bacteria to spread, splashing the pathogen from plant to plant or from the soil to the fruit surface.

Management of Bacterial fruit blotch requires an integrated approach focusing on prevention rather than cure. Because the bacteria are difficult to eradicate once established, growers should implement the following strategies:

• Sourcing certified, disease-free seed lots.
• Applying seed disinfection treatments using heat or chemicals.
• Implementing a minimum 3-year crop rotation schedule.
• Removing and destroying infected plant material immediately upon detection.
• Maintaining strict sanitation protocols for greenhouse tools and equipment.